<template>
  <div class="todo-footer">
    <label>
      <input type="checkbox" v-model="isAllCheck" />
    </label>
    <span><span>已完成{{ completeNum }}</span> / 全部{{ todos.length }}
    </span>
    <button v-show="completeNum" @click="delCompleteTodos" class="btn btn-danger">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  props: {
    todos: Array,
    delCompleteTodos: Function,
    selectAllTodos: Function
  },
  data () {
    return {
    }
  },
  computed: {
    completeNum () {
      return this.todos.reduce(function (preTotal, cur) {
        return preTotal + (cur.complete ? 1 : 0)
      }, 0)
    },
    isAllCheck: {
      get () {
        return this.completeNum === this.todos.length && this.completeNum > 0
      },
      set (value) {
        this.selectAllTodos(value)
      }
    }
  }
}
</script>

<style>
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>
